Back at the Macworld Expo in January, Apple CEO Steve Jobs said that some 20 percent of the installed base was running Mac OS X 10.5 Leopard. But do we have any sense of the current adoption rate for Leopard? Of course, Apple has the best statistics but it's unlikely that we will receive much word on adoption rates until the Worldwide Developers Conference in June. Still, aside from the semi-educated guesstimates available for a fee from analyst companies, there are several developers that provide a unique view of the installed base. Mac developer The Omni Group, a Seattle-based maker of a number of Mac OS X business applications, collects OS version information from its customers and provides it for...